1. Field of the Invention
The present invention relates to a calibration method for a visual sensor, and more particularly, to a method for calibrating a visual sensor attached to a robot by means of a calibration jig which is movably supported by means of another robot.
2. Description of the Related Art
Conventionally known are robot systems which perform assembly operation, palletizing operation, etc. for workpieces on a working line by utilizing visual information from one or more visual sensors. Also known is a technique for movably holding a visual sensor by means of a robot arm to cope with the variation of the workpiece position. According to the robot systems of this type, the visual sensor is calibrated to make sensor coordinate values to correspond to robot coordinate values before robot operation, in order to make the visual information available for the robot operation. Conventionally, for example, a camera (visual sensor in general) mounted on the robot arm is calibrated by using an exclusive-use calibration jig which is set within the range of the camera.
Generally, however, the conventional calibration jig is large-sized, and therefore, requires a wide setting space. This requirement is particularly awkward when the calibration jig is set on the working line. Further, accurately setting the conventional calibration jig takes time, so that a special jig setting mechanism must be provided for accurately setting the calibration jig.